| Abstract |
Natural thermal activity at Rotokawa, near Wairakei, is widespread and locally intense. Most of the hot springs and thermal features occur near Lake Rotokawa itself and along the Parariki Stream which drains it. The composition of these springs, the lake and the Parariki .stream waters, have been analysed on several occasions (for example, Ellis and Wilson, 1961; Ellis and Mahon, 1977; Forsythe, 1977; Henley and Middendorff, 1985). These waters are of acid pH, have chloride and sulphate as their major anions and hence are classified as being of mixed composition in terms of the E l l is and Mahon (1977) classification. Fluids discharged by geothermal drillholes at Rotokawa, by contrast, are of near neutral pH and of alkaline chloride type (Ellis & Mahon, 1977; Henley and Middendorf, 1985). However, waters of compositions different to both these types discharge along the northern and southern banks of the Waikato River, within the field , both east and west of the Fulljames Rapids. To our knowledge, there are no published analyses available of these waters although Mahon reported the composition of some in a DSIR internal report issued in 1960. Because of the present interest in the Rotokawa Geothermal area, we here record the compositions of six of these springs. |